1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor optical device.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 2010-272694 (Patent literature 1) discloses a method for fabricating a semiconductor optical device, in which different diffraction gratings can be formed by nanoimprint lithography without creating any dead area. The method for fabricating a semiconductor optical device according to Patent literature 1 uses a mold having a pattern surface including a plurality of pattern portions. The pattern portions are arranged at the period corresponding to the device size. At least one of the pattern portions differs from the other pattern portions. Using this mold, a first mask is formed on a semiconductor region by nanoimprint lithography. The semiconductor region is etched through the first mask to form a plurality of periodic structures corresponding to different pattern portions in the semiconductor region. A second mask having first and second patterns is formed on first and second desired periodic structures, respectively, in different device segments. The second mask is used to form first and second stripe mesas in the first and second segments, respectively.